<?php
/**
  * 小程序微信支付
 *  接口签名效验地址:  https://pay.weixin.qq.com/wiki/doc/api/wxa/wxa_sl_api.php?chapter=20_1
  */
namespace WeChat;

use think\facade\Config;
use think\facade\Request;

class WeChatPay {

    private $app_id;
    private $mch_id;
    private $key;
    private $openid;
    private $out_trade_no;
    private $body;
    private $total_fee;
    private $notify_url;

    /**
     * WeixinPay constructor.
     * @param $openid  string 用户openid
     * @param $out_trade_no string 订单编号
     * @param $body  string 订单描述
     * @param $total_fee string  支付金额
     * @param $notify_url string 支付回调地址
     */
    function __construct($openid='',$body='',$total_fee='',$out_trade_no='',$notify_url="")
    {
        $this->app_id = (Config::get("private"))['app_id'];
        $this->mch_id = (Config::get("private"))['mch_id'];
        $this->key    = (Config::get("private"))['key'];
        $this->out_trade_no = $out_trade_no;
        $this->body = $body;
        $this->total_fee = $total_fee;
        $this->openid = $openid;
        $this->notify_url = $notify_url;
    }

    #统一下单接口
    public function appletPay()
    {
        $data= self::applet();
        return $data;
    }
    //微信小程序接口
    private function applet() {
        //统一下单接口
        $data = $this->unifierOder();
        if($data['return_code'] === "FAIL")
        {
            returnJson(-3002,$data['return_msg']);
        }
        if ($data['result_code'] === 'FAIL') {
            returnJson(-3001,$data['err_code_des']);
        }
        $parameters = array(
            'appId' => $this->app_id, //小程序ID
            'timeStamp' => '' . time() . '', //时间戳
            'nonceStr' => self::createNonceStr(), //随机串
            'package' => 'prepay_id=' . $data['prepay_id'], //数据包
            'signType' => 'MD5'//签名方式
        );
        //签名
        $parameters['paySign'] = self::getSign($parameters);
        return $parameters;
    }


    //统一下单接口
    private function unifierOder() {
        $url = 'https://api.mch.weixin.qq.com/pay/unifiedorder';
        $parameters = array(
            'appid' => $this->app_id, //小程序ID
            'mch_id' => $this->mch_id, //商户号
            'nonce_str' => self::createNonceStr(), //随机字符串
            'body' => $this->body,
            'out_trade_no'=> $this->out_trade_no,//商户订单号
            'total_fee' => floatval($this->total_fee * 100), //总金额 单位 分
            'spbill_create_ip' => Request::ip(), //终端IP
            'notify_url' => $this->notify_url, //通知地址  确保外网能正常访问
            'openid' => $this->openid, //用户id
            'trade_type' => 'JSAPI'//交易类型
        );

        //统一下单签名
        $parameters['sign'] = self::getSign($parameters);
        $xmlData = self::arrayToXml($parameters);
        $return = self::xmlToArray(self::postXmlCurl($xmlData, $url, 60));
        return $return;
    }
    #作用：产生随机字符串，不长于32位
    private function createNonceStr($length = 32) {
        $chars = "abcdefghijklmnopqrstuvwxyz0123456789";
        $str = "";
        for ($i = 0; $i < $length; $i++) {
            $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
        }
        return $str;
    }

    private static function postXmlCurl($xml, $url, $second = 30)
    {
        $ch = curl_init();
        //设置超时
        curl_setopt($ch, CURLOPT_TIMEOUT, $second);
        curl_setopt($ch, CURLOPT_URL, $url);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, FALSE);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, FALSE); //严格校验
        //设置header
        curl_setopt($ch, CURLOPT_HEADER, FALSE);
        //要求结果为字符串且输出到屏幕上
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, TRUE);
        //post提交方式
        curl_setopt($ch, CURLOPT_POST, TRUE);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $xml);


        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 20);
        curl_setopt($ch, CURLOPT_TIMEOUT, 40);
        set_time_limit(0);
        //运行curl
        $data = curl_exec($ch);
        //返回结果
        if ($data) {
            curl_close($ch);
            return $data;
        } else {
            $error = curl_errno($ch);
            curl_close($ch);
            throw new WxPayException("curl出错，错误码:$error");
        }
    }



    //数组转换成xml
    private function arrayToXml($arr) {
        $xml = "<xml>";
        foreach ($arr as $key => $val) {
            if (is_array($val)) {
                $xml .= "<" . $key . ">" . arrayToXml($val) . "</" . $key . ">";
            } else {
                $xml .= "<" . $key . ">" . $val . "</" . $key . ">";
            }
        }
        $xml .= "</xml>";
        return $xml;
    }


    //xml转换成数组
    private function xmlToArray($xml) {
        //禁止引用外部xml实体
        libxml_disable_entity_loader(true);
        $xmlstring = simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA);
        $val = json_decode(json_encode($xmlstring), true);
        return $val;
    }
    # 生成签名
    private function getSign($Obj) {
        foreach ($Obj as $k => $v) {
            $Parameters[$k] = $v;
        }
        //签名步骤一：按字典序排序参数
        ksort($Parameters);
        $String = $this->formatBizQueryParaMap($Parameters, false);
        //签名步骤二：在string后加入KEY
        $String = $String . "&key=" . $this->key;
        //签名步骤三：MD5加密
        $String = md5($String);
        //签名步骤四：所有字符转为大写
        $result_ = strtoupper($String);
        return $result_;
    }


    #作用：格式化参数，签名过程需要使用
    #签名原串是否存在被URLencode编码的参数，微信支付的签名原串要求使用参数的原值进行签名
    private function formatBizQueryParaMap($paraMap, $bool) {
        $buff = "";
        ksort($paraMap);
        foreach ($paraMap as $k => $v) {
            if ($bool) {
                $v = urlencode($v);
            }
            $buff .= $k . "=" . $v . "&";
        }
        if (strlen($buff) > 0) {
            $reqPar = substr($buff, 0, strlen($buff) - 1);
        }
        return $reqPar;
    }

}
